Microspeakers are small sound transducers and some microspeakers may be manufactured using semiconductor technology, so that the various parts of the microspeaker are of a semiconductor material or a material that is suitable for a semiconductor-oriented manufacturing process. A microspeaker typically needs to generate high air volume displacement to gain significant sound pressure level.
For the actuation of a membrane of a microspeaker, several options exist. Some microspeaker devices utilize piezo-electric actuators or parallel-plate electro-static actuators. Another approach is to use an electrostatic comb drive structure in two planes (i.e., a first part of the comb drive structure is arranged in a first plane and a second part of the comb drive structure is arranged in a second plane) to actuate the membrane perpendicularly to the planes.
The design of a suitable digital microspeaker faces trade-offs between high frequency and low power actuation. This tradeoff may be addressed in the mechanical design of the device, namely the membrane and spring. Efforts are being made to design actuators that are fast (high resonance frequency) and at the same time are flexible enough (low resonance frequency) to allow for high actuation at low power.